The invention pertains to an improved outrigger system for power shovels, mobile cranes, and other vehicles requiring rigid ground support for safe and effective use.
In the past, vehicles requiring rigid ground support generally have been equipped with some form of telescoping beam outrigger system to give them increased stability. The most common type of outrigger system is the two-beam system in which each outrigger arm comprises an extendible beam provided at its outer end with a foot for ground contact; the beam is positioned within a second stationary beam which serves as the housing and is fixed to the vehicle. In instances where greater stability has been required an outrigger system utilizing three beams has been employed. In the three-beam system, one beam is stationary and serves as the housing and each of the other two of the beams is telescoped therein and may be extended out to produce a greater outrigger spread than is obtainable with the two-beam system. However, the three-beam system does weigh more and is more expensive than the two-beam system.
There have been numerous outrigger systems designed and patented.
For example, the Person U.S. Pat. No. 3,279,622 and the Wieschel U.S. Pat. No. 3,073,458 disclose two-beam systems in which the beam serving as the housing is disposed in the horizontal position for vehicle travel and then may be tilted downwardly when the beam is extended and the Noll et al. U.S. Pat. No. 3,021,016 discloses a system in which the extensible beam telescopes within an inclined housing and is extended downwardly and along an angular path. It is an advantage to incline the beams downwardly as it permits the use of relatively small hydraulic cylinders on the float jacks used as ground supports.
Although the prior art systems are useful and commercially acceptable, none provides a system which gives a greater reach than the two-beam system and the weight and the cost savings of the two-beam system. Therefore, there is a continuing need for improvements in outrigger systems.